Hovercraft are generally fitted with a compressor to generate the necessary air-cushion within a rubber skirt and at least one drive engine for taking straight and/or curve courses. When a curve course is taken, the hovercraft is usually steered by laterally deflecting the jet of air with a lateral rudder, such as is familiar from aircraft construction.
In such hovercraft, the bodywork tilts about the longitudinal axis of stability, the transverse axis of stability or both axes simultaneously, if the centre of gravity shifts due to varying or non-uniform loading with passengers or cargo, for example.
In the worst case, this inclination about one of the axes of stability, caused by a shift in the centre of gravity, can cause the rubber skirt of the hovercraft to dip into the water while travelling. In this case, the rubber skirt would be compressed to a more or less pronounced degree and the buoyancy of the air-cushion reduced in this area. The consequence of this is that the hovercraft dips even further into the water and could even flip over.
Another effect which occurs following a shift in the centre of gravity is thoroughly comparable to the effect of side-winds. This effect arises as a result of the varying gap between the rubber skirt and the ground or the surface of the water and the resultant varying release of the air from the air-cushion. The force component arising in this context pushes the hovercraft in the direction of the shift in the centre of gravity.
In principle, measures to compensate for the shift in the centre of gravity in hovercraft are possible by using additional trimming weights, for example. However, these measures lead to an additional weight load and, thus, to increased energy consumption.